<p><strong>This workflow confirms and quantifies 31 drugs of abuse in oral fluid (including THC) in a 4.5‑minute LC run on the </strong><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/1149"><strong>Thermo Scientific Stellar mass spectrometer</strong></a><strong> using full scan + targeted MS2 (tMS2) with both HCD and CID fragmentation. With 1 µL injection and 0.1% formic acid in water/methanol mobile phases, the method supports ~13 samples/hour (up to ~320/day continuous operation) while maintaining confirmation performance via ion ratios.</strong></p><blockquote><h5><strong>Method at a glance</strong></h5><ul><li><strong>What matrix is tested?</strong> Oral fluid</li><li><strong>How many drugs?</strong> 31 drugs of abuse (panel includes THC)</li><li><strong>Run time?</strong> 4.5 minutes</li><li><strong>Throughput?</strong> ~13 samples/hour → up to ~320 samples/day (24‑hour operation)</li><li><strong>Injection volume?</strong> 1 µL</li><li><strong>Mobile phases?</strong> 0.1% formic acid in water (A) and 0.1% formic acid in methanol (B)</li><li><strong>MS acquisition?</strong> Full scan + targeted MS2 (tMS2)</li><li><strong>Fragmentation?</strong> Compound‑optimized <strong>HCD</strong> and <strong>CID</strong> in the same targeted list</li><li><strong>Confirmation strategy?</strong> Ion ratios with ±20% tolerance (typical confirmatory approach)</li></ul></blockquote><h3><strong>Why oral fluid—and why speed matters</strong></h3><p>Oral fluid is attractive for clinical and forensic toxicology because collection is simple and the matrix aligns well with high‑volume workflows (workplace/occupational, roadside, and other settings). The challenge is building a method that’s simultaneously:</p><ul><li><strong>Broad enough</strong> for today’s drug panels</li><li><strong>Sensitive enough</strong> to reach required cutoffs</li><li><strong>Fast enough</strong> to keep sample queues under control</li><li><strong>Confirmation‑ready</strong> (consistent product ions and ion ratios)</li></ul><p>A <strong>4.5‑minute</strong> method is a practical lever here: compress runtime, raise throughput, and still keep confirmation quality by optimizing MS/MS conditions per compound.</p><h3><strong>The LC method</strong></h3><p>A short, efficient separation is the foundation of the workflow:</p><ul><li><strong>UHPLC system:</strong> <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/744"><strong>Thermo Scientific Vanquish Horizon UHPLC</strong></a></li><li><strong>Column:</strong> <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/424"><strong>Thermo Scientific Accucore Biphenyl</strong></a>, 50 × 2.1 mm, 2.6 µm</li><li><strong>Mobile phase A:</strong> 0.1% formic acid in water</li><li><strong>Mobile phase B:</strong> 0.1% formic acid in methanol</li><li><strong>Injection volume:</strong> <strong>1 µL</strong></li><li><strong>Gradient runtime:</strong> <strong>4.5 minutes</strong></li></ul><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Thermo_Fisher_Scientific_4_5_Minute_Oral_Fluid_LC_MS_Method_to_Detect_31_Drugs_of_Abuse_Using_Stellar_MS_fd3f3e8ea4.jpg" alt="Thermo Fisher Scientific: 4.5-Minute Oral Fluid LC MS Method to Detect 31 Drugs of Abuse Using Stellar MS: Figure 1: Thermo Scientific Vanquish Horizon UHPLC system." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Thermo_Fisher_Scientific_4_5_Minute_Oral_Fluid_LC_MS_Method_to_Detect_31_Drugs_of_Abuse_Using_Stellar_MS_fd3f3e8ea4.jpg 120w," sizes="100vw" width="747" height="969"></p><h3><strong>The MS method (Full scan + targeted MS<sup>2</sup> with HCD + CID)</strong></h3><h5><strong>Acquisition approach</strong></h5><p>This method uses a “two‑layer” strategy for quantitation + confirmation:</p><ol><li><strong>Full scan</strong> (broad coverage, context, quantitative support)</li><li><strong>Targeted MS<sup>2</sup> (tMS2)</strong> (confirmation‑focused product ions, ion ratios)</li></ol><h5><strong>The key differentiator: HCD and CID in one targeted list</strong></h5><p>Instead of forcing every analyte into a single fragmentation style, the method uses both:</p><ul><li><strong>HCD</strong> (beam‑type fragmentation)</li><li><strong>CID</strong> (resonance‑type fragmentation)</li></ul><h5><strong>Why that improves method development:</strong></h5><p>Drugs of abuse span multiple chemistries. A single collision approach often works “okay” for most compounds—but one or two analytes can become persistent problems (weak qualifiers, unstable ion ratios, excess noise). Having both <strong>HCD and CID</strong> available in one method lets you optimize per compound and move faster.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Thermo_Fisher_Scientific_4_5_Minute_Oral_Fluid_LC_MS_Method_to_Detect_31_Drugs_of_Abuse_Using_Stellar_MS_3_e4a95651a2.jpg" alt="Thermo Fisher Scientific: 4.5-Minute Oral Fluid LC MS Method to Detect 31 Drugs of Abuse Using Stellar MS: Figure 2: Thermo Scientific Stellar mass spectrometer." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Thermo_Fisher_Scientific_4_5_Minute_Oral_Fluid_LC_MS_Method_to_Detect_31_Drugs_of_Abuse_Using_Stellar_MS_3_e4a95651a2.jpg 245w," sizes="100vw" width="645" height="377"></p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Thermo_Fisher_Scientific_4_5_Minute_Oral_Fluid_LC_MS_Method_to_Detect_31_Drugs_of_Abuse_Using_Stellar_MS_5_88276eec6a.jpg" alt="Thermo Fisher Scientific: 4.5-Minute Oral Fluid LC MS Method to Detect 31 Drugs of Abuse Using Stellar MS: Figure 3: Full scan &amp; targeted MS2 methods, HCD and collision energies used." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Thermo_Fisher_Scientific_4_5_Minute_Oral_Fluid_LC_MS_Method_to_Detect_31_Drugs_of_Abuse_Using_Stellar_MS_5_88276eec6a.jpg 245w," sizes="100vw" width="768" height="279"></p><h3><strong>Why CID + HCD flexibility improves confirmation</strong></h3><p>In this workflow, <strong>HCD</strong> performed well for most compounds. But for <strong>buprenorphine</strong>, HCD produced one dominant product ion with additional low m/z noise and noticeable residual precursor. Using <strong>CID</strong> generated two high‑intensity product ions and delivered <strong>consistent ion ratios</strong> across the calibration range.</p><p>When your confirmation hinges on stable ion ratios, the ability to switch fragmentation mode (not just collision energy) is a method‑development advantage—especially for “problem analytes.”</p><h3><strong>Controllable ionization</strong></h3><p>Oral fluid methods often deal with limited sample volume and matrix effects. This workflow pairs low injection volume with ionization control using the Thermo Scientific OptaMax Plus HESI source.</p><ul><li>The OptaMax Plus HESI source supports high probe temperature capability (up to 650 °C).</li><li>In this study, a vaporizer temperature of 500 °C was used to help achieve sensitivity and improve relative peak areas across drugs of abuse.</li></ul><p><strong>Why this matters:</strong> If you’re injecting only 1 µL, ionization stability and efficiency can be the difference between “meets cutoff” and “misses at LOQ.”</p><h3><strong>Sample preparation</strong></h3><p>Oral fluid panels become more challenging when THC is included because most drugs of abuse are basic, while THC is largely neutral, and that can stress extraction chemistry.</p><p>In this workflow, oral fluid calibrators and samples were extracted using a mixed‑mode approach designed to recover THC alongside other drugs:</p><ul><li>Calibrators prepared across eight levels (broad dynamic range)</li><li>Extraction performed using mixed‑mode chemistry tips (SCX/WAX) in a dispersive SPE‑style workflow</li><li>Steps automated on a liquid handling platform to support high‑throughput consistency</li><li>Samples dried and reconstituted prior to LC‑MS analysis</li><li>Only 1 µL injected per run</li></ul><p>Even if your lab uses different automation or consumables, the method structure (fast LC + full scan + targeted MS2 with dual fragmentation) transfers well.</p><blockquote><h5><strong>Throughput math</strong></h5><ul><li><strong>4.5 minutes per injection</strong> → 60 / 4.5 = <strong>13.3 injections/hour</strong></li><li>That’s <strong>~13 samples/hour</strong> in typical phrasing</li><li>Over 24 hours: 13.3 × 24 = <strong>~320 samples/day</strong> (continuous operation)</li></ul><p>If you run a single shift, just scale accordingly (e.g., ~106/day for an 8‑hour shift, excluding QC and overhead).</p></blockquote><h3>Performance summary</h3><h5><strong>Sensitivity and linearity</strong></h5><ul><li><strong>Linearity</strong> from LOQs as low as <strong>0.25 ng/mL</strong> up to <strong>1,000 ng/mL</strong> (panel-dependent)</li><li>For THC specifically: <strong>LOQ at 1 ng/mL</strong>, with a dynamic range extending to <strong>1,000 ng/mL</strong> in this evaluation</li><li>Across the panel, LOQs were reported as <strong>lower than recommended confirmation cutoffs</strong> referenced in SAMHSA guidance and NSC Tier 1 cutoffs (study-specific outcome)</li></ul><h5><strong>Confirmation via ion ratios</strong></h5><ul><li>Ion ratios evaluated using <strong>±20% tolerance</strong> (typical confirmatory acceptance framework)</li><li>The workflow produced <strong>consistent ion ratios across calibrator levels</strong> for the full panel in this evaluation</li></ul><h5><strong>Case sample comparison (real-world relevance)</strong></h5><p>When compared against a validated triple quadrupole method for case study samples, the Stellar MS workflow:</p><ul><li>Confirmed the positive hits observed by the reference method</li><li>Reported a few additional positives for select analytes, attributed to lower LOQs</li><li>Highlighted an operational efficiency point: <strong>1 µL injection</strong> in this method versus <strong>20 µL injection</strong> in the compared method</li></ul><h3><strong>FAQ</strong></h3><div><div><ol><li><strong>How long does the LC‑MS run take for the 31‑drug oral fluid panel?</strong><br><strong>4.5 minutes per injection</strong> using a short UHPLC gradient.<br>&nbsp;</li><li><strong>How many drugs of abuse can Stellar MS detect in this workflow?</strong><br><strong>31 drugs of abuse</strong>, including <strong>THC</strong>, using full scan + targeted MS2.<br>&nbsp;</li><li><strong>What MS/MS approach is used?</strong><br>A combined strategy: <strong>full scan</strong> plus <strong>targeted MS2 (tMS2)</strong> for confirmation.<br>&nbsp;</li><li><strong>Why use both HCD and CID?</strong><br>Because some analytes fragment better—and produce more stable confirmation ions/ion ratios—under one mode versus the other. Using both increases flexibility and speeds method optimization.<br>&nbsp;</li><li><strong>What injection volume is used?</strong><br><strong>1 µL</strong> of extracted sample.<br>&nbsp;</li><li><strong>What mobile phases are used?</strong><br><strong>0.1% formic acid in water (A)</strong> and <strong>0.1% formic acid in methanol (B)</strong>.<br>&nbsp;</li><li><strong>How many samples can you run per day?</strong><br>At 4.5 minutes/injection, throughput is <strong>~13 samples/hour</strong> or <strong>up to ~320/day</strong> with continuous operation (actual throughput depends on QC and scheduling).</li></ol></div></div><h3><strong>What makes this workflow “easy” to develop on Stellar MS</strong></h3><p>Here’s the short list of features that directly reduce method‑development friction:</p><ul><li><strong>HCD or CID</strong> in one method → optimize per compound, not compromise</li><li><strong>Fast MS2 acquisition speeds</strong> (up to 140 Hz for MS2) → more data points across narrow peaks</li><li><strong>Fast polarity switching</strong> (true 5 ms) → supports mixed panels efficiently</li><li><strong>Adaptive RT</strong> (real‑time retention time window adjustment) → helps reduce reinjections when retention times drift (e.g., column aging) and supports method transfer from longer to shorter gradients</li><li><strong>OptaMax Plus HESI</strong> source control → supports sensitivity at low injection volumes</li></ul><p><i>If you’re building a fast oral fluid confirmation workflow—or updating an existing DOA panel—this 4.5‑minute method shows how Stellar MS can combine <strong>speed, confirmation-ready MS2, and fragmentation flexibility (HCD + CID)</strong> in a single targeted workflow. Reach out to learn how to adapt the targeted list, collision settings, and scheduling strategy to your lab’s cutoffs and throughput goals.</i></p><blockquote><p><strong>Visit us on&nbsp;</strong><a target="_blank" rel="noopener noreferrer" href="https://www.linkedin.com/showcase/72003132/admin/dashboard/"><strong><u>LinkedIn:</u></strong></a><strong>&nbsp;</strong>#MassSpectrometry #OralFluid #DrugsOfAbuse #MethodDevelopment #HighThroughput</p></blockquote>

4.5-Minute Oral Fluid LC MS Method to Detect 31 Drugs of Abuse Using Stellar MS

<p><strong>In our </strong><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/article/7741"><strong>previous article, we introduced the main types of detectors used in HPLC</strong></a><strong>. This time, we take a closer look at the performance characteristics of LC detectors and the specifications that should be considered when assessing whether a detector is suitable for a particular chromatographic separation. We will also compare the most common detector technologies and provide some practical guidance for choosing the right option for a specific application.</strong></p><h3><strong>What Defines an Ideal HPLC Detector?</strong></h3><p>With such a wide variety of HPLC detectors available, an obvious question arises: why is there no single detector that works for every application? The simple answer is that no detector can satisfy every analytical requirement at the same time. Nevertheless, most detector designs aim to achieve a similar set of desirable properties.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Figure_1_Detector_requirements_334605c913.webp" alt="KNAUER: Figure 1 - Detector requirements" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Figure_1_Detector_requirements_334605c913.webp 245w," sizes="100vw" width="1024" height="384"></p><h4><strong>1. High Sensitivity – Detecting Very Small Amounts</strong></h4><p>An ideal detector should be capable of measuring very low quantities of analyte, often in the nanogram or even picogram range. High sensitivity leads to lower limits of detection (LOD), can reduce sample preparation requirements, and is particularly valuable for applications such as impurity analysis or pharmacokinetic studies.</p><p>Some detector technologies, including fluorescence detection (FLD), electrochemical detection (ECD), and mass spectrometry (MS), can achieve extremely high sensitivity. However, this level of performance is often limited to specific classes of compounds.</p><h4><strong>2. Good Selectivity or Broad Applicability – Knowing What Is Being Detected</strong></h4><p>Selectivity describes how effectively a detector responds to the target analyte while minimizing interference from the sample matrix or mobile phase.</p><p>Depending on the analytical task, a detector may need to be highly selective, responding only to compounds with specific characteristics such as fluorescence or electrochemical activity. In other cases, broader applicability may be more important, allowing a wide range of compounds to be detected regardless of their molecular structure.</p><h4><strong>3. Linear Response and Broad Dynamic Range – Reliable Quantification</strong></h4><p>A good detector should provide a linear response across a sufficiently wide concentration range. This makes it possible to accurately quantify both major components and trace impurities within the same analytical method.</p><p>A broad linear range simplifies calibration and improves confidence in quantitative results. Detector response should also remain highly reproducible from one injection to another.</p><h4><strong>4. Compatibility with HPLC Conditions – Fitting the Chromatographic Method</strong></h4><p>An ideal detector should be compatible with both gradient and isocratic elution, commonly used mobile phases and additives, typical flow rates, and standard HPLC operating temperatures.</p><p>Poor compatibility may restrict method flexibility or force compromises in chromatographic performance. Some detectors provide excellent analytical performance but only under specific operating conditions, making them less suitable for certain methods.</p><h4><strong>5. Stability and Low Noise – Distinguishing Signal from Background</strong></h4><p>A stable baseline with minimal noise and drift improves the signal-to-noise ratio and overall data quality. This becomes especially important in long chromatographic runs, gradient methods, and trace-level analysis.</p><p>Lower baseline noise makes weak analyte signals easier to distinguish and directly contributes to improved detection limits.</p><h4><strong>6. Robustness, Ease of Use, and Maintenance – Supporting Routine Laboratory Work</strong></h4><p>For day-to-day use, a detector should be reliable over long sequences, straightforward to operate, and require as little maintenance as possible.</p><p>In routine laboratories, robustness and ease of operation can be just as important as analytical performance. Simple troubleshooting, low maintenance requirements, and limited consumable costs are major advantages, particularly in high-throughput environments.</p><h3><strong>The Reality: No Detector Offers Everything</strong></h3><p>Since no detector fulfils all these requirements perfectly, detector selection is inevitably a compromise between sensitivity, selectivity, universality, robustness, operating flexibility, and cost.</p><p>For this reason, multi-detector configurations are increasingly common in modern HPLC systems. Combinations such as UV + CAD or UV + MS make it possible to benefit from complementary detection principles within a single analytical workflow.</p><figure class="table"><table><thead><tr><th><strong>Detector</strong></th><th><strong>Principle</strong></th><th><strong>Sensitivity</strong></th><th><strong>Selectivity</strong></th><th><strong>Gradient Compatible</strong></th><th><strong>Typical Applications</strong></th></tr></thead><tbody><tr><td><strong>UV/VIS</strong></td><td>Absorption of light at selected wavelengths</td><td>ng – µg</td><td>Medium</td><td><strong>Yes</strong></td><td>Pharmaceuticals, drugs, metabolites</td></tr><tr><td><strong>Refractive Index (RID)</strong></td><td>Change in refractive index of the mobile phase</td><td>µg – mg</td><td>Non-specific</td><td><strong>No</strong></td><td>Sugars, alcohols, polymers</td></tr><tr><td><strong>Fluorescence (FLD)</strong></td><td>Excitation followed by light emission</td><td>pg – ng</td><td>High</td><td><strong>Yes</strong></td><td>Trace drugs, vitamins, fluorescent compounds</td></tr><tr><td><strong>Conductivity Detector (CDD)</strong></td><td>Measurement of changes in electrical conductivity</td><td>µg – mg</td><td>Ionic species</td><td><strong>Limited</strong></td><td>Inorganic ions, salts, electrolytes</td></tr><tr><td><strong>pH Detector</strong></td><td>Measurement of changes in proton concentration</td><td>µg – mg</td><td>pH-sensitive compounds</td><td><strong>Yes</strong></td><td>Organic acids/bases, pH monitoring</td></tr><tr><td><strong>Mass Spectrometry (MS)</strong></td><td>Ionization followed by mass-to-charge separation and detection</td><td>fg – ng</td><td>Very high</td><td><strong>Yes</strong></td><td>Proteomics, metabolomics, drugs, trace impurities, structural identification</td></tr><tr><td><strong>Electrochemical Detector (ECD)</strong></td><td>Oxidation or reduction at an electrode</td><td>pg – ng</td><td>Redox-active compounds</td><td><strong>Limited</strong></td><td>Neurotransmitters, antioxidants, drugs</td></tr><tr><td><strong>Evaporative Light Scattering (ELSD)</strong></td><td>Detection of dried analyte particles by light scattering</td><td>ng – µg</td><td>Non-volatile compounds</td><td><strong>Yes</strong></td><td>Sugars, lipids, polymers, non-UV analytes</td></tr><tr><td><strong>Charged Aerosol Detector (CAD)</strong></td><td>Detection of charged analyte particles</td><td>ng – µg</td><td>Non-volatile compounds</td><td><strong>Yes</strong></td><td>Sugars, lipids, peptides, polymers</td></tr><tr><td><strong>Multi-Angle Light Scattering (MALS)</strong></td><td>Measurement of scattered light at multiple angles</td><td>µg – mg</td><td>Molecular size/weight</td><td><strong>Yes</strong></td><td>Proteins, polymers, nanoparticles</td></tr><tr><td><strong>Viscosity Detector</strong></td><td>Measurement of pressure changes caused by solution viscosity</td><td>µg – mg</td><td>Polymers, biopolymers</td><td><strong>Yes</strong></td><td>Molecular size, branching, aggregation</td></tr><tr><td><strong>Radioactivity Detector</strong></td><td>Detection of radioactive decay from labelled analytes</td><td>pg – ng</td><td>Radioactive isotopes only</td><td><strong>Yes</strong></td><td>Radiopharmaceuticals, tracers, metabolism studies</td></tr><tr><td><strong>Chiral Detector</strong></td><td>Optical rotation or circular dichroism for distinguishing enantiomers</td><td>ng – µg</td><td>Enantiomeric selectivity</td><td><strong>Yes</strong></td><td>Pharmaceuticals, natural products, asymmetric synthesis</td></tr></tbody></table></figure><p><i>Table 1: Comparison of commonly used HPLC detector classes. (Graphic by KNAUER)</i></p><h3><strong>Critical Performance Parameters of HPLC Detectors</strong></h3><h4><strong>Data Sampling Rate</strong></h4><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Figure_2_Example_for_too_less_and_too_high_data_sampling_rate_741a53edc6.webp" alt="KNAUER: Figure 2 - Example for too less and too high data sampling rate." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Figure_2_Example_for_too_less_and_too_high_data_sampling_rate_741a53edc6.webp 245w," sizes="100vw" width="1024" height="410"></p><p>The data acquisition rate, also known as the sampling rate, is one of the most important detector settings in HPLC. It describes how many data points are recorded per second and directly influences peak representation, peak shape, area precision, and baseline noise.</p><p>The higher the sampling rate, the more data points are collected. The detector processes the measurements collected over a defined time interval and averages them, and these averaged points are then used to construct the chromatogram.</p><p>At a data rate of 5 Hz, for example, five data points are acquired every second. If too few points are collected across a chromatographic peak, the resulting peak can appear jagged, poorly defined, and analytically unreliable, as illustrated on the left side of Figure 2.</p><p>At the other extreme, a setting such as 100 Hz records 100 points each second, which is often unnecessarily high for conventional HPLC. The optimum sampling rate mainly depends on chromatographic peak width.</p><p>For most standard HPLC applications, a data rate of approximately <strong>10 to 20 Hz</strong> is sufficient to generate a smooth and symmetrical Gaussian peak.</p><p>One consequence of using an excessively high acquisition rate is increased baseline noise. Statistically, the noise of the system depends on the number of data points used for averaging and decreases with the square root of the number of averaged measurements.</p><p>Selecting an appropriate sampling rate is therefore a balance between collecting enough points to describe the chromatographic peak accurately and avoiding unnecessary noise.</p><h4><strong>Noise and Drift</strong></h4><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Figure_3_Baseline_noise_and_drift_685652e641.webp" alt="KNAUER: Figure 3 - Baseline noise and drift" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Figure_3_Baseline_noise_and_drift_685652e641.webp 245w," sizes="100vw" width="1024" height="400"></p><p>What exactly is baseline noise? In simple terms, it represents the short-term fluctuations of the detector baseline over a defined period and is expressed in the units appropriate for the particular detector.</p><p>Baseline noise is typically determined from the peak-to-peak variation of the detector signal while the mobile phase passes through the system.</p><p>All HPLC detectors exhibit a certain level of noise. Potential sources include:</p><ul><li>electronic noise,</li><li>detector cell noise,</li><li>detector instability,</li><li>temperature fluctuations,</li><li>mobile-phase effects,</li><li>and other environmental or instrumental influences.</li></ul><p>Noise directly affects detector sensitivity because it determines the <strong>signal-to-noise ratio (S/N)</strong>.</p><p>A chromatographic peak is generally considered reliably detectable when its height is at least three times greater than the calculated baseline noise. This relationship is commonly used to define the <strong>limit of detection (LOD)</strong>.</p><p>The <strong>limit of quantification (LOQ)</strong> requires a stronger signal and is typically defined as approximately ten times the baseline noise.</p><p>Another important parameter affecting sensitivity is baseline drift. Drift reflects the gradual change in detector response over time and therefore provides useful information about long-term detector stability.</p><p>It is helpful to distinguish between short-term peak-to-peak noise and longer-term baseline drift over a defined time interval. Drift can be described as the average slope or change of the baseline within a specific period.</p><p>Excessive drift may reduce sensitivity and complicate chromatographic peak integration.</p><p>Short-term baseline instability can be influenced by contamination or deterioration of detector components, while long-term drift is often related to temperature stability, detector equilibration, or changes occurring within the analytical system.</p><h3><strong>How to Select the Right HPLC Detector</strong></h3><p>There is no universally “best” HPLC detector. The correct detector is simply the one that best matches the analytical task.</p><p>When selecting a detector, several practical questions can help narrow the choice.</p><h4><strong>1. Does the analyte absorb UV light or fluoresce?</strong></h4><p>If the answer is yes, optical detectors such as <strong>UV/VIS</strong> or <strong>FLD</strong> are often the simplest and most effective options.</p><p>UV/VIS detection is widely applicable to compounds containing suitable chromophores, while fluorescence detection provides particularly high sensitivity and selectivity for naturally fluorescent or derivatized analytes.</p><h4><strong>2. Does the analyte lack a chromophore?</strong></h4><p>If UV absorption is weak or absent, detectors such as <strong>RID, ELSD, or CAD</strong> may provide a more appropriate solution.</p><p>These detector types are useful for compounds such as sugars, lipids, polymers, and other analytes that are difficult to monitor by conventional UV detection.</p><h4><strong>3. Is structural information required?</strong></h4><p>If structural information is important, <strong>mass spectrometry</strong> is usually the strongest choice.</p><p>MS provides mass-to-charge information and, when tandem mass spectrometry is used, fragmentation data that can support compound identification and structural characterization.</p><h4><strong>4. Is extremely high sensitivity necessary?</strong></h4><p>For applications requiring very low detection limits, <strong>electrochemical detection</strong> or <strong>mass spectrometry</strong> may be the most suitable options.</p><p>The exact choice depends on the chemical properties of the analyte and the required degree of selectivity.</p><h4><strong>5. Are macromolecules such as proteins or polymers being investigated?</strong></h4><p>For characterization of macromolecules, <strong>MALS</strong> and <strong>viscometry</strong> can provide valuable information about molecular weight, molecular size, branching, and aggregation.</p><p>These techniques are especially powerful when combined with size-exclusion chromatography and can provide information that is not based solely on column elution behavior.</p><p>For a more detailed discussion of detector selection, see the KNAUER blog article <i>“The way you look at it – A comprehensive guide for selecting the appropriate HPLC detector.”</i></p><p>Choosing the detection technology based on analyte properties, required sensitivity, chromatographic conditions, and the type of information needed is essential for obtaining reliable and meaningful HPLC results.</p><h3><strong>Final Thoughts</strong></h3><p>Understanding the desired characteristics and key performance parameters of HPLC detectors helps explain why different detector technologies are suited to different applications.</p><p>No single detector can provide maximum sensitivity, selectivity, universality, robustness, flexibility, and low operating cost simultaneously. Recognizing these trade-offs provides a practical framework for selecting the most appropriate detector for a given chromatographic method.</p><p>Parameters such as data sampling rate, baseline noise, drift, dynamic range, and compatibility with chromatographic conditions are just as important as the underlying detection principle itself.</p><p>In the next articles of this series, we will take a closer look at the individual HPLC detection technologies, beginning with the most widely used optical detection method: <strong>UV/VIS detection</strong>.</p>

Seeing is Believing – Detection Made Easy Part 2: Detector Characteristics

<p><strong>Our Library never stops expanding. What are the most recent contributions to LabRulezLCMS Library in the week of 17th August 2026? Check out new documents from the field of liquid phase, especially HPLC and LC/MS techniques!</strong></p><blockquote><p><span style="font-size:20px;">👉 </span><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library"><span style="font-size:20px;"><strong>SEARCH THE LARGEST REPOSITORY OF DOCUMENTS ABOUT LCMS AND RELATED TECHNIQUES</strong></span></a></p></blockquote><blockquote><p><strong>👉 Need info about different analytical techniques?</strong> Peek into <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library"><strong>LabRulezGCMS</strong></a> or <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/library"><strong>LabRulezICPMS</strong></a> libraries.</p></blockquote><p>This week we bring you posters by <strong>Agilent Technologies / ASMS, Thermo Fisher Scientific / ASMS </strong>and<strong> Shimadzu / ASMS </strong>and application note by<strong> Waters Corporation!</strong></p><h3><strong>1. Agilent Technologies / ASMS: Quantitation of N-Nitroso Duloxetine N-Nitrosamine Drug Substance Related Impurities (NDSRI) in API and Formulation by 6475 LC/TQ</strong></h3><ul><li>Poster</li><li><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/po_drug_impurities_lc_tq_tp_402_asms_2026_en_agilent_b933b9bddf.pdf"><strong>Full PDF for download</strong></a></li></ul><p>Nitrosamine impurities are nitroso derivatives where the nitroso group is attached to an amine. The active pharmaceutical ingredient (API) derived from a class of nitrosamines are known as N-nitrosamine drugsubstance-related impurities (NDSRI). Nitrosamine impurities in APIs and drug products pose safety concerns, even in small quantities, and thus are a major concern for drug makers [1].&nbsp;</p><p>Analytical methods must be sufficiently sensitive to quantify the nitrosamine of interest at levels as low as 10% of the specification limit and, where feasible, down to ≤5% of the specification limit, for the determination of the limit of detection. LC/MS/MS is an inherently selective and highly sensitive analytical technique that is well suited for the identification and quantification of trace-level impurities at extremely low concentrations. Consequently, LC/MS/MS has been widely adopted within the pharmaceutical industry, particularly for nitrosamine analysis [2-3].&nbsp;</p><p>Therefore, manufacturers must develop and qualify a dedicated analytical method that is appropriate for the specific sample matrix and targeted NDSRIs. An LC/MS/MS method based on multiple reaction monitoring (MRM) was developed for the detection and quantification of the N-nitroso duloxetine NDSRI impurity over a concentration range of 0.5 to 40 ppb (absolute standard concentration), using an atmospheric pressure chemical ionization (APCI) source on an Agilent 6475A LC/TQ instrument.</p><h4><strong>Experimental</strong></h4><ul><li><strong>MS:</strong> <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?mainauthorItems=10&amp;search=6475"><strong>6475 Triple Quadrupole LC/MS System</strong></a></li><li><strong>Column:</strong> <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?mainauthorItems=10&amp;search=Poroshell+HPH+C18"><strong>Poroshell HPH C18</strong></a> (4.6*150mm, 2.7µm)</li></ul><h4><strong>Conclusions</strong></h4><ul><li>A highly sensitive and robust MRM LC/MS/MS method was developed for the quantitation of N-nitroso duloxetine in duloxetine hydrochloride API and finished formulation using the Agilent 6475A LC/TQ.&nbsp;</li><li>The optimized chromatographic conditions provided effective separation of the analyte from the API, placebo, and formulation matrices, ensuring reliable quantitation.&nbsp;</li><li>The calibration curve was linear over the concentration range of 0.5-40 ng/mL, with 1/x weighting. R and R2 values were observed for both to be greater than 0.99.&nbsp;</li><li>Recovery studies demonstrated efficient sample extraction, with recoveries ranging from 92-99% in API samples and 109-116% in pellet formulations at the LOQ, specification, and 200% specification levels.&nbsp;</li><li>The method also showed excellent reproducibility across all evaluated concentration levels, confirming its suitability for routine analysis.</li></ul><h3><strong>2. Shimadzu / ASMS: Non-Targeted Analysis of Per- and Polyfluoroalkyl Substances in Environmental Extracts by Microflow LC-QToF Coupled with Multi-spray ESI</strong></h3><ul><li>Poster</li><li><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/TP_562_Non_Targeted_Analysis_of_Per_and_Polyfluoroalkyl_Substances_in_Environmental_Extracts_by_Microflow_LC_Q_To_F_Coupled_with_Multi_spray_ESI_c2a7e1d5bf.pdf"><strong>Full PDF for download</strong></a></li></ul><p>Targeted screening methods are well established for monitoring Perand polyfluoroalkyl substances (PFAS) in environmental samples. However, PFAS comprise a large and evolving class of compounds, creating a need to screen existing, emerging, and transformation products across diverse matrices. Non-targeted Analysis (NTA) allows for the confirmation of suspected PFAS in the environment, but the sample characterization is often limited by analytical sensitivity. Microflow (0.5 – 40 µL/min) coupled with a multi-nozzle emitter enhances sensitivity by improving desolvation. When this is coupled to a high mass accuracy and resolution Quadrupole Time-ofFlight Mass Spectrometer (QToF), capable of data-dependent and independent MS/MS, PFAS characterization of unknown analytes is possible. In this study, various environmental extracts were processed and screened using NTA for PFAS compounds.</p><h4><strong>Methods</strong></h4><p>A <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?mainauthorItems=1&amp;search=Nexera+Mikros"><strong>Shimadzu Nexera Mikros LC</strong> </a>was used to introduce the sample to a Newomics DuoESI source with an M3 emitter on a <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?mainauthorItems=1&amp;search=9050"><strong>LCMS-9050 QToF MS</strong></a> (Fig. 1). A direct injection on an octadecyl column without delay column was performed. Direct injection was chosen over trapand-elute configuration to minimize selectivity bias caused by the trap column.&nbsp;</p><h4><strong>Conclusion</strong></h4><p>With the increased sensitivity of microflow LC-QToF coupled with multi-spray ESI with DIA acquisition, Insight Explore aided in NTA PFAS analysis. When paired with Insight Discovery and Profiler, a streamlined batch data processing workflow with statistical analysis was shown to effectively handle complex environmental matrices and their analyses.</p><h3><strong>3. Thermo Fisher Scientific / ASMS: Robust and sensitive quantitation of 18 steroids in human serum using Thermo Scientific TSQ Certis Triple Quadrupole mass spectrometer</strong></h3><ul><li>Poster</li><li><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/po_004707_lsms_18_steroids_tsq_certis_clinical_po004707_asms2026_na_en_244c52437b.pdf"><strong>Full PDF for download</strong></a></li></ul><p>Accurate quantification of endogenous steroids in human serum is essential for biomonitoring physiological functions such as hormone regulation, reproduction, and immune response in clinical research laboratories. Liquid chromatography–tandem mass spectrometry (LC–MS/MS) is the gold standard for steroid analysis due to its superior sensitivity, selectivity, and multiplexing capability compared to immunoassays. However, steroid measurements remain challenging because of low endogenous concentrations and complex serum matrices. Here, we describe a robust and sensitive LC–MS/MS method for the simultaneous quantification of 18 steroids in human serum using the Thermo Scientific TSQ Certis triple quadrupole mass spectrometer (Figure 1). The method leverages advanced ion source design and fast acquisition to deliver enhanced sensitivity, stability and throughput suitable for high-volume laboratory workflows.</p><h4><strong>Materials and methods</strong></h4><h5><strong>Liquid chromatograph – mass spectrometry&nbsp;</strong></h5><p>Samples were analyzed on a <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/744"><strong>Thermo Scientific Vanquish Horizon UHPLC system</strong></a> coupled to the <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/2207"><strong>TSQ Certis MS</strong></a><strong> </strong>operated in selected reaction monitoring (SRM) mode. The mobile phase composition, analytical column details, LC gradient, and overlaid extracted ion chromatograms (EICs) are shown in Figure 3.&nbsp;</p><h5><strong>Data analysis&nbsp;</strong></h5><p>Data were acquired and processed using <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/77"><strong>Thermo Scientific TraceFinder software</strong></a> (v 5.2).</p><h4><strong>Conclusions&nbsp;</strong></h4><p>A sensitive and robust LC–MS/MS method was developed for simultaneous quantification of 18 steroids in human serum using the Vanquish Horizon UHPLC and TSQ Certis MS with OptaMax Plus ion source. The method demonstrated excellent linearity, accuracy, and reproducibility across a wide dynamic range. Optimization of MS conditions, particularly vaporizer temperature, significantly improved sensitivity. Overall, the workflow delivers high sensitivity, selectivity, and long-term stability, providing a reliable solution for high-throughput steroid analysis in clinical and research settings.</p><h3><strong>4. Waters Corporation: Alkaline-hydrolysis Method for PFAS in Textiles and Textiles Products by Xevo™ TQ-S micro with ACQUITY™ UPLC™ H-Class Plus System</strong></h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/720009443_en_0ab4914d72.pdf"><strong>Full PDF for download</strong></a></li></ul><div><div><section><div><div><div><div><div><div><h5><strong>Benefits&nbsp;</strong></h5><ul><li>Alkaline hydrolysis method (EN 17681-1:2025) used for preparing textiles, coated textiles and textile products for PFAS analysis allowed the inclusion of side-chain fluorinated polymers&nbsp;</li><li>Extraction method provided significant advantages in handling complex textile matrices by creating clear extracts free from dispersions, settleable solids and particulates&nbsp;</li><li>Protected the high-value LC-MS/MS components from potential damage&nbsp;</li><li>The method improved analytical sensitivity, reproducibility and accuracy, enabled cost-effective and timeefficient PFAS analysis maintained high analytical quality even for challenging high-matrix samples</li></ul><p>Many PFAS are linked to health concerns because of their ability to interfere with the body’s hormone systems, acting as endocrine disruptors also, linked to other toxic effects. Since textiles come into direct and prolonged contact with the skin, there is an increased risk of human exposure—especially for babies and children.4 In addition, PFAS pose significant environmental concerns. These “forever chemicals” do not readily break down and can be released during manufacturing, washing and disposal, allowing them to enter water pathways and persist in the environment. As a result, testing for PFAS has become increasingly important in the textile industry to demonstrate supply chain transparency, build consumer trust and protect brand reputation.</p><p>Synthetic fluorinated chemicals are categorized into two main groups - non-polymeric PFAS and polymeric PFAS, known for their use as water and grease repellent, heat resistant finishes in textiles, upholstery, leather, apparel, carpet and other industrial applications such as packaging, firefighting foams, non-stick cookware, etc. (Figure 1). PFAS are fluorinated substances contain at least one fully fluorinated methyl or methylene carbon atom (without any H/Cl/Br/I atom attached to it), i.e. with a few noted exceptions, any chemical with at least a perfluorinated methyl group or a perfluorinated methylene group.2 PFAS are classified as long chain and short chain based on their perfluorinated carbon chain length. Short chain fluorinated polymers encompasses a diverse range of chemistries, categorized according to their generic chemical and repeating units structures. Few examples are: derivatives of fluorotelomers, perfluoropolyethers with varying carbon chain lengths and acrylates, epoxylates, urethane, silicones of repeated units based structures.3 Polyfluoroalkyl substances such as fluorotelomer alcohols (FTOHs) contain C–H bonds, rendering them more susceptible to degradation. The ethoxylates in fluorotelomers-methacrylate break down to FTOH whereas polymeric fluorinated urethanes, acrylates break down to PFCAs (non-polymeric and polymeric side chain fluorinated polymers). In contrast, perfluoroalkyl substances such as PFOS and PFOA are extremely persistent due to their fully fluorinated carbon chains.&nbsp;</p><p>In alkaline hydrolysis methods, methanolic aqueous sodium hydroxide is used to break down precursor PFAS such as FTOHs, branched side chain PFAS. This process releases terminal perfluorinated carboxylic acids (PFCAs), which can then be measured. However, the efficiency of hydrolysis varies among different PFAS compounds and the presence of interfering substances such as organic matter or other chemicals in the sample matrix can inhibit the cleavage and detection of these analytes.</p><h4><strong>Experimental</strong></h4><ul><li><strong>LC system:</strong> <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/198"><strong>ACQUITY UPLC H-Class Plus System</strong></a> and SMFTN fitted with PFAS kit</li><li><strong>Column(s):</strong> <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/1823"><strong>XBridge™ BEH™ C18 5 µm Column</strong></a>, 4.6 x 100 mm&nbsp;</li><li><strong>MS system: </strong><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/209"><strong>Xevo TQ-S micro Mass Spectrometer</strong></a></li></ul><h4><strong>Conclusion&nbsp;</strong></h4><p>By strictly following the critical steps of the alkaline hydrolysis method using methanolic aqueous sodium hydroxide (NaOH) both freely extractable PFAS and those previously bound within side-chain fluorinated polymers such as esters linked to fluorotelomer alcohols (n:2 FTOHs, where n = 4, 6, 8, 10, 12), can be effectively extracted. This approach also safeguards the LC-MS/MS instrumentation from blockages, damage, or contamination by preventing polymer accumulation and matrix interferences.&nbsp;</p><p>The analytical method using the ACQUITY UPLC H-Class Plus System and Xevo TQ-S micro LC-MS/MS System was found to be sensitive, reproducible and accurate, enabling cost-effective and time-efficient PFAS analysis in chemically processed textiles, coated textiles and textile products whilst maintaining high analytical quality even for challenging high-matrix samples.</p></div></div></div></div></div></div></section></div></div>

News from LabRulezLCMS Library - Week 34, 2026

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A unique company dedicated to serving science helping our customers drive productivity and accelerate results. Through our premier brands – Thermo Scientific, Applied Biosystems, Invitrogen, Fisher Scientific and Unity Lab Services.

Thermo Fisher Scientific

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Based in Berlin, KNAUER is a medium-sized, owner-managed company that has been serving the sciences since 1962. We develop and manufacture scientific instruments of superior quality for liquid chromatography, including: Analytical HPLC/UHPLC, Preparative HPLC, Fast protein liquid chromatography (FPLC), Multi-column chromatography/Simulated moving bed (SMB) chromatography. High pressure dosing, in-line detection systems, and osmometry are additional business areas.

KNAUER

Thermo Scientific ISQ™ EC/EM Single Quadrupole Mass Spectrometer

Enhance your IC or LC analysis with ISQ EC/EM mass spectrometers. Enjoy fast setup, high sensitivity, and reliable quantification—even in complex samples—with easy, seamless system integration.

<h4><strong>Thermo Scientific™ ISQ™ EC Single Quadrupole Mass Spectrometer</strong></h4><p><strong>Add mass spectrometry (MS) to your IC and LC analyses for access to the valuable data that only MS can provide. The new, easy-to-use Thermo Scientific™ ISQ™ EC Single Quadrupole Mass Spectrometer seamlessly integrates with ion chromatography (IC) and high performance liquid chromatography (HPLC) systems. Both novices and experts alike can quickly master MS to gain more insights from every sample.</strong></p><h5><strong>Gain more insights</strong></h5><ul><li>Higher sensitivity and more accurate quantitation</li><li>Chromatographic peak mass confirmation, eliminating false negatives and false positives</li></ul><h5><strong>Resolve complexity</strong></h5><ul><li>Improved resolution of analytes in complex matrices</li><li>Better selectivity</li><li>Resolve co-eluting peaks using their mass-to-charge ratio</li></ul><h5><strong>Easily mastered</strong></h5><ul><li>Save time spent on user training with integrated tools to help master MS</li><li>Experience hassle-free, seamless integration with your IC or LC system</li><li>Save time using the Thermo Scientific™ <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/76"><strong>Chromeleon™ Chromatography Data System (CDS) software</strong></a> for data analysis, which also has embedded control of the ISQ EC mass spectrometer</li></ul><h4><strong>Thermo Scientific™ ISQ™ EM Single Quadrupole Mass Spectrometer</strong></h4><p>Adding mass spectrometry (MS) to your liquid chromatography (LC) analyses gives you access to the valuable data that only MS can provide. The new, easy-to-use ISQ™ EM Single Quadrupole Mass Spectrometer seamlessly integrates with LC systems for reliable, robust, and easy LC-MS routine analysis with an extended mass range for more flexibility. Detect and quantify a variety of analytes by choosing to use either heated electrospray ionization (HESI) or atmospheric pressure chemical ionization (APCI). Integrated software allows both novices and experts to quickly master MS to gain more insights from every sample.</p><h5><strong>Gain more insights</strong></h5><ul><li>Extended mass range enables you to detect and quantify small and large molecules</li><li>Durable atmospheric pressure ionization (API) source with two interchangeable probes included, enabling HESI or dual HESI/APCI</li><li>Sensitive and accurate quantitation of more samples</li><li>Chromatographic peak mass confirmation to eliminate false negatives and false positives</li></ul><h5><strong>Resolve complexity</strong></h5><ul><li>Consistent response even with complex matrices</li><li>Better selectivity and sensitivity with chromatographic peak mass confirmation</li><li>Resolution of co-eluting peaks via mass-to-charge ratio</li></ul><h5><strong>Easy mastery</strong></h5><ul><li>Reduce time spent on user training with integrated tools to help master MS</li><li>Unique software translates analyte physical properties into optimal method parameters, helping novice and experts develop methods and improve productivity</li><li>Hassle-free, seamless integration with existing LC systems</li><li>Facilitate data analysis with Thermo Scientific™ <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/76"><strong>Chromeleon™ Chromatography Data System (CDS) software</strong></a>, which features embedded control of the ISQ EM mass spectrometer</li></ul><h4><strong>Key Features ISQ™ EC/EM Single Quadrupole Mass Spectrometers:</strong></h4><ul><li><strong>Mass Range:</strong>&nbsp;<ul><li><strong>EC:</strong> 10–1250 m/z with unit mass resolution</li><li><strong>EM:</strong> 10–2000 m/z with unit mass resolution</li></ul></li><li><strong>Polarity Switching:</strong> 25 ms (in HESI mode)</li><li><strong>Scan Rate:</strong> Up to 20,000 Da/sec</li><li><strong>Sensitivity:</strong><ul><li><i>HESI Positive:</i> 10 pg Reserpine, 400:1 RMS at 400 μL/min</li><li><i>HESI Negative:</i> 20 pg p-Nitrophenol, 500:1 RMS at 400 μL/min</li></ul></li><li><strong>Gas Requirements:</strong> Nitrogen (≥ 99% purity), 30 L/min @ 90–110 psig</li><li><strong>Power Supply:</strong> 100–240 V, 50/60 Hz</li><li><strong>Dimensions:</strong> 52 (H) × 42 (W) × 91 (D) cm</li><li><strong>Weight:</strong> Approx. 71 kg (157 lb)</li><li><strong>Unit Size:</strong> Each</li></ul>

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News from LabRulezLCMS Library - Week 34, 2026

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